The present invention relates to technique of realizing serial communication of a system bus connecting between processing units constituting a process control system which makes control while monitoring equipment.
Recently, in the field of household appliances for general use such as personal computers, the high-speed serial bus represented by SATA (Serial Advanced Technology Attachment) and PCI Express (Peripheral Component Interconnect Express) (registered trademark) is being used instead of conventional parallel bus. Furthermore, even in computer systems used in the industrial field, a demand for cost reduction is enhanced with high-speed operation, high performance and improvement of maintenance of processing units. In order to satisfy these requirements, it is studied that the system bus configured by parallel communication in the prior art is realized by serial communication.
For example, PCI-SIG and PCI Express Base Specification discloses the technique of realizing high-speed serial bus and PCI-SIG and PCI Express Base Specification and PCT International Publication WO97/12312 disclose the method of attaining hot plug using parallel bus.